Antibodies (Abs) are widely used to localized, purify and study scarce proteins, including membrane proteins involved in neurotransmission. Abs of known epitope specificity are especially useful tools. The amino acid sequence of many receptors and ion channels are known, and this information can be used to make synthetic peptides and produce sequence- specific Abs, able to cross-react with the cognate protein. Also, recombinant proteins can be obtained in large amounts by biosynthetic approaches, corresponding to the sequence of cloned scarce proteins, or to long segments of it. The facility will provide the services related to peptide synthesis and production of peptide specific polyclonal As(pABs), and devise methods to obtain and characterize anti-peptide pAbs able to cross-react with the native cognate protein. It will also provide the services related to production of sequence specific mAbs (mAbs) using as immunogens recombinant proteins corresponding to long sequence regions of the protein being studied, further by identification of the epitope(s) recognized by the mAbs, employing short overlapping synthetic peptides spanning the sequence of the recombinant protein. Studies that used synthetic peptide sequences as representative structural elements of the cognitive protein have been proven to have a good predictive value to identify sequence regions involved in formation of surface domains of functional importance. Thus, we propose to extend the services previous provided by this Core Facility to include production of large panels of overlapping peptides screening the sequence of the proteins studied by the different investigators, for structural studies of surface domains for which probes are available (e.g. agonists, antagonists, toxins, ligand-competitive Abs).